## Release v0.51.247 — Release HO (stage-q19)
Backend correctness fix.
### Fixed
| Issue | Author | Fix |
|-------|--------|-----|
| #3505 | @franksong2702 | **Reasoning effort is coerced to a level the active model/provider actually supports** before each request, instead of being sent verbatim and rejected. `openai-codex` `gpt-5` no longer gets `max` (→ `xhigh`); `o1`/`o3`/`o4` clamp to `low`/`medium`/`high`. Coercion only steps *down* (never escalates); `none`/unset preserved. The capability filter is applied across heuristic / models.dev / Copilot / LM Studio paths. |
This is the narrow, correct fix for the detection gap that #3431 tried to address by removing the chip-visibility gate (which we shelved). The chip-visibility gate is **untouched** (Codex confirmed) — `get_reasoning_status`/`_applyReasoningChip` still hide the chip for unconfirmed models.
### Review fix absorbed (Codex + self-flagged)
The first cut **dropped** a configured effort for *unrecognized* models, because capability detection returns `[]` for both "known-unsupported" and "simply-unknown" (custom providers, aggregator-rewritten ids, new releases) — that's a behavior change vs master (which sent it verbatim) and would silently disable reasoning. Fixed: an **empty** capability set now **preserves** the configured effort (provider stays the final authority; worst case = the same rejected request master already produces, i.e. no regression). Known-bad clamps return *non-empty* filtered sets, so they still degrade correctly. Nathan chose this "preserve-for-unknown" behavior. + regression test.
### Gate
- Full pytest suite: **7548 passed, 0 failed**
- ruff: CLEAN · 48 reasoning tests pass (incl. preserve-for-unknown + codex-clamp + never-escalate)
- Codex (regression): SHIP-ONLY-WITH-FIXES (unknown-model drop) → fixed → **SAFE TO SHIP**
- Verified empirically: gpt-5/codex max→xhigh, o3 max/xhigh→high, unknown high→high (preserved), none/unset preserved
Co-authored-by: franksong2702 <franksong2702@users.noreply.github.com>
- Covers the openai-codex + supports_reasoning=False path now that
Codex routes through _models_dev_reasoning_efforts.
- Mirrors the existing false-suppression test for symmetry.
- 9/9 tests pass.
- Remove openai-codex special case that called github_model_reasoning_efforts()
- Codex now falls through to _models_dev_reasoning_efforts() (full efforts)
- GitHub/Copilot still use the GitHub helper (caps at high)
- Added regression tests for both behaviors
